Female Hormone Health, Fertility & Vitality | Dr. Natalie Crawford

KEYPOINTS

• 01

  Women have the most eggs before birth and lose them steadily from then on

  Crawford, a reproductive endocrinologist and infertility specialist who also holds a nutrition science degree, explains that a female fetus has about 6–7 million eggs at around 20 weeks of gestation. More than half are gone by birth. She compares the ovary to a vault: a group of eggs leaves it every month for life, more of them when more remain, and only one is usually ovulated.

• 02

  AMH estimates ovarian reserve, but the pill can lower the reading

  Anti-Müllerian hormone (AMH) is made by the granulosa cells around each follicle: more eggs in the vault means higher AMH. Long-term birth control pill use suppresses those cells and can make AMH read up to 30% lower, which is fully reversible. A low result on the pill needs interpreting, sometimes by stopping the pill and retesting.

• 03

  The fertile window is five days ending on ovulation day

  Sperm can survive about 5 days and the egg about 24 hours. The day before and the day of ovulation give the best odds. Daily sex during the window gives the highest chance per cycle, but if that causes stress or burnout, Crawford suggests sex every other day from 5–6 days before expected ovulation, aiming for the day before and the day of ovulation.

• 04

  Smoking, vaping and heavy drinking harm egg quality

  Cigarettes deplete the egg supply, bring menopause earlier and raise the risk of eggs with abnormal chromosomes by disrupting the meiotic spindles that separate chromosomes. Vaping chemicals are linked to lower IVF success. Chronic alcohol drives inflammation that affects both eggs and sperm, and Crawford says the only acceptable amount during pregnancy is zero. Huberman cites a survey in which 15% of American women reported using cannabis during a known pregnancy.

• 05

  The pill has real benefits and real risks

  Because you don't ovulate on the pill, the ovary goes through less of the repeated healing that can give rise to ovarian cancer, and long-term use sharply cuts that risk. The pill raises clotting factors, so it's avoided in smokers and people with high blood pressure. Testing for Factor V Leiden is an inexpensive blood test but isn't routine before prescribing.

• 06

  Egg numbers and quality fall steeply after 37

  Both egg count and quality drop more profoundly from about 37. Crawford urges anyone planning two or three children starting at 35–36 to check AMH, the sperm and the fallopian tubes early. Later family starts, chronic illness, autoimmune disease and obesity are pushing infertility up as birth rates fall.

• 07

  Egg freezing technology has improved dramatically

  Ten years ago only about 40% of frozen eggs survived thawing, versus about 90% today. Embryos, made of many cells, survive better still. Egg freezing and IVF involve the same retrieval and differ only in what the lab does afterward. Freezing sperm costs around $400 and is far simpler. Problems from older paternal age become clear around 50.

• 08

  Menopause means low estrogen, and early hormone therapy is now recommended

  Menopause, on average at 51–52, brings higher risks of dementia, osteoporosis, heart disease, stroke and death, plus hot flashes and vaginal atrophy. Crawford says OB-GYNs now recommend hormone replacement started at the onset of menopause. The harms reported in the Women's Health Initiative study came largely from women who had gone 10 or more years without estrogen before starting hormones.